Process for lubricating metal surfaces during working of the same



United States Patent 3 267,037 PROCESS FOR LUBRKIATING METAL SURFACES DURING WORKING OF THE SAME Bill Mitacek and John P. Graham, Bartlesville, 0kla., as-

signors to Phillips Petroleum Company, a corporation of Delaware No Drawing. Filed May 27, 1963, Ser. No. 283,609 1 Claim. (Cl. 252-59) This invention relates to an improved process for lubricating metal surfaces during the working of the same. In another aspect, it relates to an improved process of lubricating aluminum during cold-rolling of the same.

In working or fabricating metals, such as in the coldrolling of aluminum, it is a conventional practice to lubricate the surfaces of the metal. Many different lubricants have been proposed, patented or used for this purpose. Among the lubricants which have been used are animal oils, vegetable oils, mineral oils, and mixtures of these and water-oil emulsions. Animal and vegetable oils are effective lubricants, but they have certain disadvantages in that they are rather expensive, are not good coolants, and are easily oxidized with the resultant development of rancidity. Furthermore, animal and vegetable oils, having high carbon residue values, have been unsatisfactory in that unless they are removed from the worked metal prior to its being annealed, they will leave stains in the form of carbon deposits on the metal when it is subsequently annealed. While straight mineral oils are satisfactory with respect to their cost, cooling properties, and stability, they, as do the animal and vegetable oils, also have a disadvantage in that unless they are removed from the worked metal prior to its being annealed, they will leave a stain on the surface of the annealed metal. Water-oil emulsions are advantageous in that they may easily be removed from metal surfaces by washing with water prior to annealing, but this step in itself complicates the working process. Water-oil emulsions have a further disadvantage in that with repeated use as cold-working lubricants, the water tends to evaporate from the water-oil emulsions, thereby changing the ratio of water to oil. Since the ratio of water to oil should be kept as uniform as possible to obtain optimum results, frequent analysis of the lubricant is required thereby adding complexity to the process.

Accordingly, it is an object of this invention to provide an improved process of lubricating metal surfaces during working of the same. Another object is to provide a process of lubricating aluminum during coldrolling of the same, using a novel lubricant for this purpose which will not leave a stain on the surface of the rolled stock when the same has been subsequently subjected to annealing. Further objects and advantages of this invention will become apparent to those skilled in the art from the following description and appended claim.

We have discovered that the working of metal surfaces can be improved by lubricating the same with a lubricant comprising a highly branched chain paraffin hydrocarbon, preferably mixtures thereof, boiling in the range of 335 to 700 F., preferably in the range of 400 to 660 F., and having a minimum flash point of 125 F., preferably a minimum flash point of 210 F. Generally, these highly branched chain hydrocarbons have 9 to 20 carbon atoms per molecule, at least two of which are tertiary or quaternary carbon atoms. Mixtures of these highly branched chain hydrocarbons contain a minimum of 90 percent branched chain hydrocarbons and such mixtures are substantially completely saturated and are essentially odorless. As impurities, the mixtures contain predominantly straight chain saturated hydrocarbons. Typical 3,267,037 Patented August 16, 1966 highly branched chain hydrocarbons which can be used include 3,3-diethylhexane, 2,2,3,3-tetramethylheptane, 2,4,5,7-tetramethyloctane, 4,5-diisopropyloctane 3,3,4,4- tetramethylhexane, 2,3,7-trimethyloctane, 2,6-dimethyl-3- isopropylheptane, 2,6,11,1S-tetramethylhexadeeane, and the like, preferably mixtures thereof.

The highly branched chain hydrocarbons used as lubricants in this invention can be obtained from any suitable source. Convenient methods for their preparation include alkylation of isoparaffins with mono-olefins using such catalysts as hydrogen fluoride, aluminum chloride, sulfuric acid, or the like. Especially useful mixtures of these highly branched chain hydrocarbons are those produced as by-products, termed heavy alkylates, in a hydrogen fluoride alkylation process. Such heavy alkylates can be topped, de-oiled, or clay treated as required or desired to provide fractions having the desirable boiling point range. An example of a method which can be used for the production of mixtures of highly branched chain hydrocarbons is that disclosed by Legatski in US. Patent No. 2,442,011.

The highly branched chain hydrocarbons, or mixtures thereof, can be used per se as lubricants in the working of metal surfaces, and they will not leave a stain on the surface of the metal after the same has been worked and annealed. However, if desired, such highly branched chain hydrocarbons can be mixed with the usual additives, such as oiliness agents like fatty oils, fatty vegetables, vegetable oils, soaps and the like.

The improved lubricating process of this invention can be used in the working of metals in generally, preferably non-ferrous metals. The invention is especially applicable in the cold-rolling of aluminum or aluminum alloys, followed by annealing. The metal, in the form of sheets or strips and/ or the working rolls, can bev sprayed, brushed,'or otherwise contacted with the improved rolling lubricant of this invention to provide a film of lubricant on the surfaces of the metal being worked. The lubricated metal is passed through the bit of the two rolls a sufficient number of times to reduce the metal to the desired thickness or gauge. Sufficient lubricant is used to keep the working rolls from softening and to keep the friction between the rolls and the metal :being rolled to a minimum. Annealing of the rolled stock can be performed in a conventional gas-fired furnace or the like, where the rolled stock is exposed to elevate temperatures, e.g., 600 to 900 F., for varying periods of time, e.g., 2 to 5 hours. The lubricant used during the working of the metal, according to this invention, need not be washed off or removed prior to the annealing step, since it is cleanly vaporized during the annealing step without staining the metal surfaces. After the temperature of the rolled stock reaches the desired peak temperature, e.g. 900 F., it can be immediately allowed to cool.

The objects and advantages of this invention are illustrated in the following examples, but it should be understood that the various lubricants described in these examples, and the conditions of use, etc., should not be construed to unduly limit this invention.

Several grades or mixtures of the highly branched chain hydrocarbon lubricants of this invention, prepared from the heavy alkylate produced by the aforesaid hydrogen fluoride alkylation process, were evaluated by a stain test. In this test, 0.8 ml. quantity of the lubricant was placed on a clean aluminum test plate (polished to a mirror finish) and the plate was placed in an electrical furnace where it was held at a temperature of about 650 F. for about 30 min., the test plate being horizontally placed so that the lubricant did not run off. At the end of the test period, the plate was removed and visually observed for stain. In all cases, the annealed test plate remained bright and free from stain. The

lubricants A, B, C, D and E used in these examples, essentially of a mixture of highly branched chain paraffin and their physical properties, are set forth below in hydrocarbons, said mixture of hydrocarbons boiling in Table I. the range of 400660 F. and having a minimum flash TABLE I Lubricants Specification Test method A B O D E Viscosity, cs. at 100 F. ASTM D445-61 9.17 7. 04 5.01 3. 2. 4 Flash point, 000, ASTM D92-57 275 295 260 220 210 Sulfur, weight percent ASTM D126662T 0. 01 0. ()1 Pour point, ASTM 1397-51..-- -45 -50 -50 Bromine number ASTM D1l58*59T 11. 0 10.0 6. 0 3. 5 1. 5 Refractive index at c ASTM D1281-61. 1 4527 1 4530 1 4461 1 4392 1 4337 Infrared branched vinyl, groups/1,000 carbon atoms 0 Distillation, F ASTM D8662. Initial boiling point 530 544 468 438 433 5% evaporated 541 547 496 447 436 10% evaporatetL a 545 549 499 451 437 evaporated 557 557 515 469 443 evaporated. 588 567 535 493 450 95% evaporatetL.-. 656 585 569 561 460 Dry point A 587 573 461 End point- 659 589 576 587 466 Various modifications and alterations of this invention point of 210 F. and containing a minimum of perwill become apparent to those skilled in the art from the cent branched chained hydrocarbons. foregoing description and example without departing 25 from the scope and spirit of this invention, and it should References Cited by the Examiner be understood that this invention is not to be unduly UNITED STATES PATENTS limited to that set forth herein for illustrative purposes. 2,256,693 9 /1941 Wright 252 59 X Wec1a1m: 30 2,605,224 7/1952 Jahn 252-405 In the art of cold rolling metals in which the rolled 2,962,401 11/1960 G i ki 148 11.5

metals are substantially annealed at elevated temperatures, the step of applying to the surface of the metal DANIEL XMAN Prmm'y Examiner being rolled a non-staining liquid lubricant consisting C. O. THOMAS, W. H. CANNON, Assistant Examiners. 

